Welcome! I'm Anna Cabré

a climate physicist
exploring new paths for a sustainable future

Ph.D. in Physics | Homeward Bound 2019 fellow

About Me

I was born in Barcelona in 1980. I now see myself as an oceanographer, but I have a multidisiplinary background. I studied physics in Barcelona, and then did a PhD in cosmology on the large scale structure of the Universe at the Institute of Space Sciences. In 2009, I moved to Philadelphia (USA) for a postdoctoral appointment on gravitational lensing and modified gravity at the University of Pennsylvania. It was amazing and I learned a lot about 'doing science' and 'academia', but it turns out that the Universe is a bit too far away from the ground for me, so I slowly transitioned into studying the Earth, the climate, and the oceans at the Dept of Earth and Environmental Sciences, and much later in the Institute of Marine Sciences back in Barcelona. Meanwhile, life happened. Now I am raising two little people, live between Barcelona and Germany, and swim, bike, write, play the flute and dance as often as I can.

My goal now is to explore outside of the theoretical world where my research lives (inside the computer) and focus more on policy and science communication, if only to change the world a bit with my little grain of sand. As a first step, I am participating on a leadership program for women that culminates with an adventure to Antarctica. Bring me to Antarctica!

Short bio

  • Research associate at the Institute of Marine Sciences (Barcelona) and University of Pennsylvania (Philadelphia) (July 2018-now)
  • 'Beatriu de Pinós' fellow (co-funded with Marie S Curie actions) at the Institute of Marine Sciences (Barcelona) (2016-2018) with J.L. Pelegri
  • Postdoctoral researcher at the Dept. of Earth and Environmental Sciences at UPenn (2012-2015), with Irina Marinov (thanks for taking me in!)
  • Postdoctoral researcher at the Dept. of Physics at UPenn (2009-2012), with Bhuvnesh Jain
  • Doctoral thesis at the Institute of Space Sciences (Barcelona) on cosmology (2004-2008) (download thesis), with E. Gaztañaga
  • Physics Degree at the University of Barcelona (1998-2003)
Download CV

Homeward Bound leadership program

I have been selected to participate in a one-year long program to enhance leadership in female scientists with the purpose of participating in policy decisions concerning climate change. This program culminates with a 3-week cruise to Antarctica with on-board lectures. See the media coverage about my participation in Homeward Bound.

"HB is a global leadership initiative that aims to network and upskill 1000 women with a STEMM background over the next 10 years. The program will provide them with the leadership, strategic and communication capabilities to help promote women into decision-making positions affecting policy around the sustainability of our planet."

Why Antarctica?

Antarctica remains the only continent without permanent citizens in it. Yet, parts of it have already felt the consequences of human emitted carbon ( See). Antarctica is pure nature in its most brutal shape. Being there with similar minded women will provide an ideal setting for collaboration, learning, and a story to tell, essential to inspire the necessary change.

Why now?

If not now, when? Climate change is already happening and the consequences are noticeable in many parts of the world, with the worst outcomes in the most powerless countries. As a climate scientist, I believe that I have no excuse for not trying. I think that a better world is possible and I am hoping to make a contribution. For an extensive (and very carefully reviewed) study on the effects of climate change see the IPCC report.

Why me?

We scientists are often so focused on our research and the need to constantly apply for funding (look for jobs, move around) that we often forget how important communicating science is. How are our knowledge and skills valuable to the society and to the future of the Earth if we do not share them? I have the science background but I know that this is not enough to start the change that we need. I have the drive and perseverance to bring my knowledge higher up, but I could certainly use some leadership lectures.

Why women?

We are severly underrepresented in leadership positions. Somewhere in the process, a big proportion of women are lost for a variety of reasons, one of the most important is that society still prizes and expects men to take up these positions. It seems fair to give a push to women to work towards closing the gender gap and see what women have to offer to the leadership table. Only good things can come out of this initiative.

Sponsor me?

Visit my sponsor webpage with more details on the program, which is subsidized through donors but only to half of the total cost. If you know of a company, institution, school that would be interested in sponsoring me, please drop me an email. The 6 Spanish participating in the program have united to work as a team. Visit our webpage EllasLideran.cc

Climate and Oceanography

I study the output of Earth System Models to understand the large scale spatial and temporal variability of oceanic and atmospheric climate patterns, once the everyday weather has been averaged out. Weather is to climate what your mood today is to your personality. I am interested in predicting the mid and long-term changes due to climate warming and to separate these changes from natural variability. In other words, I am interested in the long-term personality changes of our Earth. See below the main lines of research I am involved with.

See publications

Transfer between the subtropical and tropical gyres in the South Atlantic

Modelization of ocean phytoplankton

Southern Ocean open-sea convection and teleconnections

Phytoplankton satellite observations

Oxygen Minimum zones in the Pacific

Evolution of fisheries with climate change

South Atlantic transfer

We study regions that contribute to the northward heat transfer that occurs in the top 1000m of the Atlantic Ocean. The South Atlantic plays a crucial role in the returning limb of the Atlantic meridional overturning circulation that originates with sinking of cold and salty sater in the North Atlantic; the South Atlantic is the only basin that transfers heat equatorward from the subtropics to the tropics to compensate (northward) for the southward export of North Atlantic Deep Water (NADW), but it has traditionally not studied as much as the homologous North Atlantic. We have used a lagrangian technique to track the origin and path of the waters that end up in the subtropical or tropical gyres. We study the volume transport associated to each route, the paths of propagation, the spatial and depth structure of these paths, and the heat and freshwater gain along these pathways.

Open-ocean deep convection in the Southern Ocean

During the mid-1970s, a huge hole in the sea ice (polynya) opened during winter in the Weddell Sea, east of the Antarctic Peninsula, and was observed with satellites that had been launched few years before. The polynya closed and has only reemerged during the last 2 winters. It is open-ocean strong water column mixing that brings relatively warm water from the deep ocean to the surface and melts the ice. All the models that have this mixing events predict a stoppage of mixing with climate warming. We have explored the variability in Southern Ocean surface temperatures that result from pulses in open-ocean deep convection in the Weddell Sea (in the Southern Ocean), with a long 1000-year control experiment with pre-industrial conditions that exhibits strong convective events every ~70 years. We have found that fluctuations in Southern Ocean surface temperatures modify the energetic balance at the top of the atmosphere and the propagation of heat transport in both the atmosphere and the ocean. The atmospheric changes result for example in a weakening of the Southern Ocean westerlies, a warming of the atmosphere, and an increase in precipitation towards the southern tropics. The oceanic changes result in a strengthening of the formation of Antarctic bottom waters, and a weakening of the Meridional Overturning circulation during convective events. See this communication release. Here a copy of the published paper.

Oxygen Minimum Zones in the Pacific

We analyse simulations of the Pacific Ocean oxygen minimum zones (OMZs) from 11 Earth system model contributions to the Coupled Model Intercomparison Project Phase 5, focusing on the mean state and climate change projections. The eastern tropical regions are often low in oxygen due to sluggish ventilation and strong biological activity that consumes lots of oxygen. Oxygen is essential for most types of oceanic life, hence it is crucial to understand these regions and the predicted evolution within the next century. The simulations tend to overestimate the volume of the OMZs, especially in the tropics and Southern Hemisphere. Under the climate change scenario RCP8.5, all simulations yield small and discrepant changes in oxygen concentration at mid depths in the tropical Pacific by the end of the 21st century due to an almost perfect compensation between warming-related decrease in oxygen saturation and decrease in biological oxygen utilization. See publication (pdf)

Phytoplankton modeling

Understanding how global phytoplankton populations will respond to climate change is critical, since phytoplankton provide the ultimate food source for all marine organisms and draw down atmospheric CO2 by fixing inorganic carbon into organic matter via photosynthesis. We analyzed for the first time all 16 Coupled Model Intercomparison Project Phase 5 models with explicit marine ecological modules to identify the common mechanisms involved in projected phytoplankton biomass, productivity, and organic carbon export changes over the twenty-first century in the RCP8.5 scenario (years 2080–2099) compared to the historical scenario (years 1980–1999). All models predict decreases in primary and export production globally of up to 30 % of the historical value. ("Consistent global responses of marine ecosystems to future climate change across the IPCC AR5 earth system models")
We also analyzed how phytoplankton change in the Southern Ocean. The models predict a zonally banded pattern of phytoplankton abundance and production changes within four regions: the subtropical ( 30 to 40 S), transitional (40 to 50S), subpolar (50 to 65S) and Antarctic (south of 65S) bands. We find that shifts in bottom-up variables (nitrate, iron and light availability) drive changes in phytoplankton abundance and production on not only interannual, but also decadal and 100-year timescales – the timescales most relevant to climate change. ("A latitudinally banded phytoplankton response to 21st century climate change in the Southern Ocean across the CMIP5 model suite")
See this outreach article summarizing our research.

Phytoplankton observations from satellite color data

Recent technological evolution has allowed the observation of phytoplankton abundance from space. When the Earth is not covered in clouds, satellites can see through to the surface of the Earth, and transform the ocean color into phytoplankton abundance with algorithms that use Chlorophyll as an indicator of mini-algae presence. Chlorophyll is a green pigment found in plants, responsible for absorbing the light needed for the photosynthesis. Hence, greener parts of the ocean have more biological productivity.
However, Chl and phytoplankton abundance do not follow a linear relation, as Chlorophyll can photoadapt differently depending on the light, nutrients, and temperature. I have been working with Tihomir Kostadinov and the group at UPenn on a novel bio-optical algorithm that retrieves size-partitioned phytoplankton carbon from ocean color satellite data, independently from Chlorophyll. This alrogithm is based on backscattering; the size of phytoplankton changes the spectrum of the light when scattering. We have studied the seasonality, interannual variability (associated to well known indices such as 'El Niño'), and long-term trends for phytoplankton and the different sizes in comparison to Chl, and have detected interesting differences across biomes.
Carbon-based phytoplankton size classes retrieved via ocean color estimates of the particle size distribution
Phenology of Size-Partitioned Phytoplankton Carbon-Biomass from Ocean Color Remote Sensing and CMIP5 Models
Inter-comparison of phytoplankton functional type phenology metrics derived from ocean color algorithms and Earth System Models

Effect of climate change on fisheries

Climate change is going to affect the habitat conditions that ultimately affect fisheries. Changes in temperature, stratification of the water column, wind patterns, food supply, all these modify the biomes where fish live. I have collaborated with a group from the Marine Research Division at AZTI that use the output of models to predict how the habitat of tuna, eel, anochovy is going to change in the next 50-100 years. See the recently published paper on 'Historical trends and future distribution of anchovy spawning in the Bay of Biscay'


Google Scholar
Research Gate

The Universe

I did my doctoral thesis on the large-scale structure of the Universe in the Institute of Space Sciences and a postdoc at the University of Pennsylvania. My focus was to compare data from large-scale surveys with standard cosmological theories with the objective of determining the best theories (and ruling out theories uncompatible with observations) and constraining the values of the different components of the Universe. This is my research keyword cloud, created with Scimeter.

See publications in cosmology Download thesis

Integrated Sachs-Wolfe effect

Gravitational lensing
Credit: NASA/ESA

Baryonic acoustic oscillations

Modified gravity in dwarf galaxies

Dark Energy Survey

Sloan Digital Sky Survey

Physicists currently believe that the universe is composed basically of dark energy (70%) and dark matter (25%), both unknown components. The rest is made of known (baryonic) matter.
The standard cosmological model starts with Big Bang, followed by a rapid period of expansion of the universe called inflation. After that, tiny almost homogeneous fluctuations that conform the primordial universe, start to grow while universe expands now in a relatively slow rhythm. 380,000 years after the Big Bang, the temperature is low enough to make the universe become neutral after the recombination of atoms with electrons. Photons are almost free of interactions since then and reach us in the form of a Cosmic Microwave Background (CMB). We can measure the spatial anisotropy spectrum of CMB temperatures and compare it to the expected spectrum of acoustic oscillations. This comparison provides a direct geometrical test from which we can deduce that universe is flat or nearly flat. This can be explained if we introduce a new constituent in the universe apart from matter, the dark energy. Dark energy acts as anti-gravity that accelerates the expansion and is also observed through standard candles Supernovae Ia. Although there is a well motivated model that can explain observations, neither dark matter nor dark energy are known elements, so it is important to use the large amount of newly available data to obtain tighter constraints on the constituents of the universe, the evolution of growth perturbations, the expansion history, and also to explore other alternatives, such as modification of gravity.
I worked with data from the Sloan Digital Sky Survey and with simulations that were prepared for Dark Energy Survey, that is now ongoing. I mostly used Luminous Red Galaxies as my favourite tracer of dark matter. These galaxies are intrinsically bring and hence can be seen further away and trace a larger volume than normal galaxies. I studied the redshift space distortions that arise due to the peculiar motion of galaxies, when shifts in the light spectrum due to the movement of galaxies are confused with the shifts due to the expansion of the Universe. These distortions are one of the ways that cosmologists have to study directly the growth of perturbations in the space-time. I also worked on the Integrated Sachs Wolfe effect (ISW), another direct way to study the growth trhough the evolution of gravitational potentials. ISW is detected when cross-correlating the remote cosmic microwave map with any more recent map that traces Large Scale Structure. Photons from the CMB can be modified when passing through the potential wells created by the large scale strucutre, if for example these potentials change with time. We can detect dark energy thanks to ISW, since we need a dark energy dominated universe to have an evolution of gravitational wells (although this could also be achieved by having a non-flat universe). Luminous Red Galaxies galaxies also allowed us to detect the baryon acoustic peak in the averaged correlation function, and we also detected it in the line-of-sight direction, which means a direct calculation of the Hubble constant! I also worked with photometric surveys (angular projections, photometric redshifts). I worked on modeling weak gravitational lensing as a way to also determine the dark matter in the Universe. Light from far away galaxies is bended when passing through all the dark matter between them and us. Finally, I was studying how to detect (or rule out) a type of modified gravity in dwarf (small) galaxies.


ADS publication list
astro-ph archive

Science outreach


Anna Cabré Albós